<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title>Document</title>
  <script src="jquery-3.6.0.min.js"></script>
</head>
<body>
  <div class="father">
    <div class="son1">子元素1</div>
    <div class="son2">子元素2</div>
    <div class="son3 remove">子元素3</div>
  </div>
  <script>
    $('div').find('.son1').css('font-weight', '800');
    $('.son2').parent().css('background-color', 'pink');
    console.log($('.son3').hasClass('remove'));
  </script>
</body>
</html>